a(b^3-c^3) +b(c^3-a^3)+c(a^3-b^3)
=> a(b-c)(b^2+bc+c^2)+bc^3-ba^3+ca^3-cb^3
=>a(b-c)(b^2+bc+c^2)-(cb^3-bc^3)-(ba^3-ca^3)
=>a(b-c)(b^2+bc+c^2)-bc(b-c)(b+c)-a^3(b-c)
=>(b-c)(ab^2+abc+ac^2-cb^2-bc^2-a^3)
=>(b-c)(
a(b3-c3)+b(c3-a3)+c(a3-b3)
=a.b3+b.c3+c.a3-a.c3-b.a3-c.b3
=(a.b3-b.a3)+(b.c3-c.b3)+(c.a3-c3.a)
=(ab.b2-ba.a2)+(bc.c2-bc.b2)+(ca.a2-ca.c2)
=ab(a2-b2)+bc(c2-b2)+ca(c2-a2)
có hằng đẳng thức nào ko